Quiet stream to raging torrent.
How to stop girls smoking.
and A new look at fingerprints.
What are tomorrow's scientists up to today?
A chance to find out as teams of schoolchildren from all over the country compete in the last of four heats for the Sunday Times 'Science Fair' trophy. The winners of next week's final will represent Great Britain at an international Science Fair in Holland.
Finding out the answers, pupils from Sexey's Grammar School, Bruton, Somerset; Oak Park Secondary Girls School, Havant, Hants; Gateway School, Leicester
The Judges: Dr John Lenihan, Professor George Porter, Professor Eric Laithwaite
Presented by Paddy Feeny